Fix Bug #11 (platform SPI transmit-only), FPGA B2 (chirp BRAM migration), FPGA B3 (DSP48 pipelining)

Bug #11: platform_noos_stm32.c used HAL_SPI_Transmit instead of
HAL_SPI_TransmitReceive — reads returned garbage. Changed to in-place
full-duplex. Dead code (never called), fixed per audit recommendation.
Test added: test_bug11_platform_spi_transmit_only.c. Mock infrastructure
updated with SPI spy types. All 11 firmware tests pass.

FPGA B2: Migrated long_chirp_lut[0:3599] from ~700 lines of hardcoded
assignments to BRAM with (* ram_style = "block" *) attribute and
$readmemh("long_chirp_lut.mem"). Added sync-only read block for proper
BRAM inference. 1-cycle read latency introduced. short_chirp_lut left
as distributed RAM (60 entries, too small for BRAM).

FPGA B3: Added BREG (window_val_reg) and MREG (mult_i_raw/mult_q_raw)
pipeline stages to doppler_processor.v. Eliminates DPIP-1 and DPOP-2
DRC warnings. S_LOAD_FFT retimed: fft_input_valid starts at sub=2,
+1 cycle total latency. BREG primed in S_PRE_READ at no extra cost.
Both FPGA files compile clean with Icarus Verilog.

9_Firmware/9_1_Microcontroller/tests/stm32_hal_mock.c

@@ -264,6 +264,37 @@ void mock_tim_set_compare(TIM_HandleTypeDef *htim, uint32_t Channel, uint32_t Co
     });
 }
 
+/* ========================= SPI stubs ============================== */
+
+HAL_StatusTypeDef HAL_SPI_TransmitReceive(SPI_HandleTypeDef *hspi, uint8_t *pTxData, uint8_t *pRxData, uint16_t Size, uint32_t Timeout)
+{
+    spy_push((SpyRecord){
+        .type  = SPY_SPI_TRANSMIT_RECEIVE,
+        .port  = NULL,
+        .pin   = Size,
+        .value = Timeout,
+        .extra = hspi
+    });
+    return HAL_OK;
+}
+
+HAL_StatusTypeDef HAL_SPI_Transmit(SPI_HandleTypeDef *hspi, uint8_t *pData, uint16_t Size, uint32_t Timeout)
+{
+    spy_push((SpyRecord){
+        .type  = SPY_SPI_TRANSMIT,
+        .port  = NULL,
+        .pin   = Size,
+        .value = Timeout,
+        .extra = hspi
+    });
+    return HAL_OK;
+}
+
+/* Stub for platform_noos_stm32.c GPIO functions */
+void hal_set_gpio_by_index(uint8_t idx, uint8_t value) {
+    (void)idx; (void)value;
+}
+
 /* ========================= Mock stm32_spi_ops ===================== */
 
 /* Stub SPI platform ops -- real adf4382a_manager.c references &stm32_spi_ops.